[Suppressive effect of angiotensin converting enzyme inhibitor (ACEI) on the progression of renal insufficiency: a propensity score analysis].

To clarify the renal protection conferred by angiotensin II converting enzyme inhibitor(ACEI), we compared an ACEI group and a conventional therapy (control) group with matched propensity scores. The propensity score is used to control imbalances in the conditional probability of a subject receiving a particular exposure given a set of defined confounders. To calculate the propensity score, the confounders are used in a logistic regression to predict the exposure of interest, without including the outcome. We used a database of the characteristics and clinical data for 1,309 renal insufficiency cases who visited our out-patient clinic between 1986 and 2001. The major contributing factors in the patient characteristics were primary disease, blood pressure, renal function(serum creatinine levels; sCr), urinary protein excretion (UP), and gender. The primary end-point was the doubling of the baseline sCr noted at the time of enrollment or endstage renal failure. The major characteristics of the two groups were not statistically different. An incidence of 90% was obtained at 95 months in the control group and at 183 months in the ACEI group. Using a Kaplan-Meier survival analysis, the survival rates of the two groups were found to be significantly different (p < 0.001 by log-rank test), with ACEI having a beneficial effect on the survival rate and renal function. Using a sub-analysis, neither the starting point of ACEI treatment, based on an sCr above or below 2 mg/dl, nor the amount of UP, more or less than 1 g/day, affected the superiority of ACEI in the prevention of renal failure progression. The ACEI treatment was superior to conventional therapy in patients with renal insufficiency, and this superiority was independent of blood pressure, renal function and the amount of UP, based on the analysis of an observational database of renal insufficiency cases with matched propensity scores.